1. Technical Field
The present invention relates to an apparatus and method for intra-oral stimulation of the trigeminal nerve.
2. Description of the Related Art
Insomnia has been defined as “the subjective problem of insufficient or nonrestorative sleep despite an adequate opportunity for sleep. It occurs at one time or another in almost all adults.”1 It is a universal problem.
Insomnia has been linked to a reduction in NREM stage 3–4 or delta brainwaves that characterize the deepest pattern of sleep. Delta brainwaves, so named for their association with the four D's of disease, dystrophy, damage and deep sleep, are large and slow with a frequency of less than 4 per second.2 Electroencephalogram (EEG) measurements indicate that, on average, children and young adults have more NREM stage 3–4 sleep than older adults,3 and a decrease in Stage 3–4 NREM sleep is a typical symptom of aging past age 55.4 
Insomnia can be addressed in a variety of ways. First, a number of appliances are available to reduce or eliminate physiological impediments to the body's natural sleep cycle.
Appliances for sleep therapy principally address lung, breathing (e.g., genioglossus contraction failure during inspiration) and snoring problems, which commonly accompany sleep disorders such as sleep apnea. Second, sleep therapies are available that are intended to induce sleep. Such sleep therapies include well-known drugs, such as benzodiazapines (e.g., lorazepam and flurazepam). Unfortunately, these drugs create physical dependence, often cause adverse reactions, and require higher dosages as tolerance increases with use. Discontinuation of benzodiazapine use is very difficult, and withdrawal symptoms have been reported months after use of even low dosages. Perhaps as a consequence of the negative side effects of drug therapies, melatonin, a hormone naturally occurring in the brain, is taken by millions of Americans to induce sleep with varying rates of success.
In view of the widespread incidence of insomnia and the absence of a sleep therapy that is generally successful in inducing sleep without side effects, the present invention therefore recognizes that it would be useful and desirable to provide a sleep therapy that successfully induces sleep without the negative side effects that accompany traditional drug therapies.
Another common problem experienced by millions of Americans is that of chronic stress, which can defined as frequent activation of the body's natural adrenal response in response to circumstances that do not warrant “fight or flight.” Chronic stress is characterized by accelerated pulse and respiration rates and is a significant risk factor for heart disease, the leading cause of death in the U.S.
Conventional methods of addressing stress include, among others, drug therapies, relaxation and meditation techniques, and lifestyle changes. As with the drug therapies for insomnia, the drug therapies for stress (and the related malady of anxiety) can have significant adverse side effects. Consequently, sufferers of stress often turn to alternative methods of addressing stress, such as lifestyle modification and relaxation and meditation techniques. However, these alternatives do not alleviate the chronic stress for all individuals or in all circumstances. Therefore, a need remains for a stress therapy that successfully alleviates stress and induces relaxation without the negative side effects that accompany traditional drug therapies.
It should also be noted that it is known to control or treat medical, psychological or neurological disorders (including sleep disorders) by application of electrical signals directly to the afferents of a patient's trigeminal and/or glossopharyngeal nerves. For example, U.S. Pat. No. No. 5,540,734 to Zabara discloses an implantable or external neurostimulator (i.e., generator) that can be utilized to directly stimulate the afferents of the trigeminal and/or glossopharyngeal nerves of a patient to treat sleep disorders, eating disorders, neuropsychiatric disorders, and a host of other ailments.
In order to provide better understanding of Zabara's teaching, reference is now made to FIG. 3, which illustrates a median sagittal section of a human brain 100. Brain 100 comprises a number of major structures, including cerebral hemisphere 101, occipital gyrus 121, optic chiasma 109, corpus callosum 102, cerebellum 108, third ventrical 103, cerebral peduncle 104, medulla oblongata 107, mesencephalon (midbrain) 105, and pons 106. As shown in the expanded view, the sensory nuclei 117 and motor nucleus 111 of the trigeminal nerve are embedded in mesencephalon 105. The motor root 112 and sensory root 113 of the trigeminal emerge through pons 106 and merge to form trigeminal (Gasserian) ganglion 110, which then divides into the ophthalmic, maxillary, and mandibular divisions 114–116 of the trigeminal nerve. Zabara teaches the stimulation of the trigeminal nerve through electrodes attached directly to one of ophthalmic, maxillary, and mandibular divisions 114–116 or to trigeminal (Gasserian) ganglion 110. As will be appreciated upon inspection of FIG. 3 and also FIG. 4B, which depicts a cross-section of the human brain taken along line 1—1 of FIG. 4A, Zabara's technique requires highly invasive surgery to the center of the brain through some of its most delicate structures in order to attach electrodes to the trigeminal nerve.
The invasive nature of the surgery required to implant electrodes attached to the afferents of the trigeminal and/or glossopharyngeal nerves and the high risk of disabling complications and side effects suggest that the treatment disclosed by Zabara should be reserved for extreme cases, and then only under the close supervision of a medical professional. Consequently, there remains a need for a therapy for treating or controlling sleep disorders and/or stress that is non-invasive and appropriate for the millions of individuals that suffer from sleep disorders and stress.